Well preserved relief specimens of the dendroid graptolites Dendrograptus rigidus Bulman, 1936 and Acanthograptus sp. have been discovered in a siltstone within the basal Engervik Member of the Elnes Formation. The specimens are the first dendroid graptolites found in the Middle Ordovician of the Oslo Region, although planktic graptolites are common in the shales of the Elnes Formation.